Methods and apparatus for mapping modulation symbols to resources in OFDM systems

ABSTRACT

A transmission resource in a time domain subframe is divided into a plurality of equal duration resource elements in a time and frequency domain, the plurality of resource elements are segregated into a plurality of resource regions, information to be transmitted is modulated to generate a sequence of modulation symbols at a transmitter, the sequence of modulation symbols is mapped into the plurality of resource elements in the plurality of resource regions, and the modulation symbols are transmitted via a plurality of antennas using the respective corresponding resource elements to a receiver. The mapping of the modulation symbols in at least one resource region is independent of a certain control channel information that is carried in the time domain subframe, and the mapping of the modulation symbols in at least another resource region is dependent upon that certain control channel information.

CLAIM OF PRIORITY

This application is a continuation of U.S. Non-Provisional patentapplication Ser. No. 14/017,137 filed Sep. 3, 2013, which is acontinuation of U.S. Non-Provisional patent application Ser. No.13/007,367 filed Jan. 14, 2011, now U.S. Pat. No. 8,526,392, which is acontinuation of U.S. Non-Provisional patent application Ser. No.12/076,938 filed Mar. 25, 2008, now U.S. Pat. No. 7,885,176, and claimspriority to U.S. Provisional Patent Application No. 60/924,861 filed onJun. 1, 2007. The above-identified patent documents are incorporatedherein by reference.

BACKGROUND

The present disclosure relates to a method for mapping modulationsymbols to resources in a communication system, and more specifically, amethod for mapping modulation symbols into different resource regions ina communication system, and another method for mapping modulationsymbols of multiple code blocks into resources in a communicationsystem.

DESCRIPTION OF RELATED ART

Telecommunication enables transmission of data over a distance for thepurpose of communication between a transmitter and a receiver. The datais usually carried by radio waves and is transmitted using a limitedtransmission resource. That is, radio waves are transmitted over aperiod of time using a limited frequency range.

In a contemporary communication system, the information to betransmitted are first encoded and then modulated to generate multiplemodulation symbols. The symbols are subsequently mapped intotransmission resource. Usually, the transmission resource available fordata transmission is segmented into a plurality of equal duration timeand frequency slots, so called resource elements. A single resourceelement or multiple resource elements may be allocated for transmittingthe data. When data is transmitted, a control signal may accompany thedata to carry information regarding the allocation of the resourceelements for the current data transmission. Therefore, when a receiverreceives the data and the control signal, the receiver may derive theinformation regarding resource allocation used for data transmissionfrom the control signal and decodes the received data using the derivedinformation.

In Third (3^(rd)) Generation Partnership Project Long Term Evolution(3GPP LTE) systems, certain resource elements are allocated for controlsignal transmission. Therefore, the data symbols may be mapped into theresource elements that are not allocated for control signaltransmission. Each data transmission carries information bits of one ormultiple transport blocks. When a transport block is larger than thelargest code block size, the information bits in a transport block maybe segmented into multiple code blocks. The process of dividing theinformation bits in a transport block into multiple code blocks iscalled code block segmentation. Due to the limited selection of codeblock sizes and the attempt to maximize packing efficiency during thecode block segmentation, the multiple code blocks of a transport blockmay have different sizes. Each code block will be encoded, interleaved,rate matched, and modulated. Therefore, the data symbols for atransmission may consist of modulation symbols of multiple code blocks.

SUMMARY

It is therefore an object of the present disclosure to provide animproved method for transmission.

It is another object to provide an improved mapping scheme for mapmodulation symbols.

According to one aspect of the present disclosure, a method fortransmission may be provided to divide a transmission resource in asubframe into a plurality of equal duration resource elements in timeand frequency domain, segregate the plurality of resource elements intoone or a plurality of resource regions, modulate information to betransmitted to generate a sequence of modulation symbols at atransmitter, map the sequence of modulation symbols into the pluralityof resource elements in the plurality of resource regions, andtransmitting the modulation symbols via one or a plurality of antennasusing the respective corresponding resource elements to a receiver. Themapping of the modulation symbols in at least one resource region, i.e.,first resource region, is independent of a certain control channelinformation that is carried in said time domain subframe, and themapping of the modulation symbols in at least another resource region,i.e., second resource region, is dependent upon said certain controlchannel information that is carried in said subframe.

The certain control channel information may be a control channel formatindication.

The method may further include interleaving the sequence of modulationsymbols before mapping the modulation symbols into the resourceelements.

The sequence of modulation symbols may be sequentially mapped intoresource elements within a plurality of multiplexing symbols in theresource regions starting from a multiplexing symbol having a smallestindex in the time domain. One example of a multiplexing symbol is anOFDM symbol in an Orthogonal Frequency Division Multiplex (OFDM) system.

The mapping of the sequence of modulation symbols may start from theresource elements within the at least one first resource region. If thenumber of the modulation symbols is more than the resource elements inthe at least one first resource region, the remaining modulation symbolsmay be mapped into the resource elements within the at least one secondresource region.

The multiplexing symbols may be mapped in each resource region in anincreasing order starting from a multiplexing symbol having a smallestindex in the time domain in that resource region.

After mapping the modulation symbols into the resource elements withinthe multiplexing symbols, the modulation symbols within eachmultiplexing symbols may be interleaved in the frequency domain.

Alternatively, in the first resource region, the multiplexing symbolsmay be mapped in a decreasing order, and in the second resource region,the multiplexing symbols may be mapped in an increasing order.

Still alternatively, in the first resource region, the multiplexingsymbols may be mapped in an increasing order, and in the second resourceregion, the multiplexing symbols may be mapped in a decreasing order.

The method may further include calculating the number of availableresource elements in the at least one first resource region to obtain afirst number, calculating the number of available resource elements inthe at least one second resource region to obtain a second number,mapping the first number of modulation symbols into the resourceelements within the at least one first resource region, and mapping thesecond number of modulation symbols into the resource elements withinthe at least one second resource region.

The method may further include transmitting a control channel signalcarrying said certain control channel information via the transmitter tothe receiver, decoding at the receiver the control channel signal toderive said certain control channel information, determining whichresource elements within the at least one second resource region areused for the transmission of the modulation symbols, collecting themodulation symbols transmitted in a resource region selected from amongthe at least one first resource region to generate a first data packet,decoding the first data packet, determining whether the first datapacket decodes, and if the decoding of the first data packet fails,recursively collecting the modulation symbols transmitted in saidresource region and other resource regions selected from among the atleast one first resource region and the at least one second resourceregion, and decoding the collected modulation symbols until thecollected modulation symbols decodes.

If the decoding of the control channel signal fails, the receiver mayrecursively collect and decode the modulation symbols transmitted insaid resource region and other resource regions selected from among theat least one first resource region until the collected modulationsymbols decodes.

According to another aspect of the present disclosure, a method fortransmission may include dividing a transmission resource in a subframeinto a plurality of equal duration resource elements in a time andfrequency domain, segmenting the information to be transmitted togenerated a plurality of code blocks, each code block including aplurality of information bits with at least one code block containing asmaller number of information bits than at least another code block,encoding the code blocks to generate a plurality of coded bits,modulating the plurality of coded bits in the code blocks to generate asequence of modulation symbols at a transmitter, assigning roughly equalnumber of resource elements to each of the plurality of code blocks witha slightly larger number of resource elements assigned to the codeblocks with larger sizes and a slightly smaller number of resourceelements assigned to the code blocks with smaller sizes, andtransmitting the modulation symbols via one or a plurality of antennasusing the respective corresponding resource elements to a receiver.

According to another aspect of the present disclosure, a method fortransmission may include dividing a transmission resource in a timedomain subframe into a plurality of equal duration resource elements ina time and frequency domain, segregating the plurality of resourceelements into a plurality of resource regions, comprising at least onefirst resource region and at least one second resource region, each ofthe first resource regions and the second resource regions comprising atleast one multiplexing symbol, each multiplexing symbol corresponding toa time slot, and each multiplexing symbol comprising a plurality ofresource elements corresponding to respective frequency sub-carriers,segmenting the information to be transmitted to generated a plurality ofcode blocks, each code block including a plurality of information bits,encoding the code blocks to generate a plurality of coded bits,modulating the plurality of coded bits in the code blocks to generate asequence of modulation symbols at a transmitter, mapping at least onemodulation symbol in each code block into the resource elements in theat least one first resource region, with the mapping being independentof a certain control channel information that is carried in said timedomain subframe, and transmitting the modulation symbols via a pluralityof antennas using the respective corresponding resource elements to areceiver.

The method may further include mapping at least one modulation symbol ineach code block into the resource elements in the at least one secondresource region, with the mapping being dependent on the certain controlchannel information that is carried in said time domain subframe.

The method may further include assigning roughly equal number ofresource elements in one of the at least one first resource region toeach of the plurality of code blocks.

The method may further include assigning roughly equal number ofresource elements in one of the at least one second resource region toeach of the plurality of code blocks.

The method may further include assigning roughly equal number of codedbits in one of the at least one first resource region to each of theplurality of code blocks.

The method may further include assigning roughly equal number of codedbits in one of the at least one second resource region to each of theplurality of code blocks.

The method may further include assigning a selected number of resourceelements in one of the at least one first resource region to each of theplurality of code blocks to obtain roughly equal coding rate among theplurality of code blocks.

The method may further include assigning a selected number of resourceelements in one of the at least one second resource region to each ofthe plurality of code blocks to obtain roughly equal coding rate amongthe plurality of code blocks.

The method may further include assigning a selected number of coded bitsin one of the at least one first resource region to each of theplurality of code blocks to obtain roughly equal coding rate among theplurality of code blocks.

The method may further include assigning a selected number of coded bitsin one of the at least one second resource region to each of theplurality of code blocks to obtain roughly equal coding rate among theplurality of code blocks.

According to still another aspect of the present disclosure, atransmitter may be constructed with a modulator modulating informationto be transmitted into a plurality of modulation symbols, a mapping unitmapping the plurality of modulation symbols into a plurality of resourceelements in a time domain subframe, with the time domain subframecomprising a plurality of resource regions, with the mapping of themodulation symbols in at least one resource region being independent ofa certain control channel information, and a plurality of transmittersfor transmitting the modulation symbols using the corresponding resourceelements.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure, and many of theattendant advantages thereof, will be readily apparent as the samebecomes better understood by reference to the following detaileddescription when considered in conjunction with the accompanyingdrawings in which like reference symbols indicate the same or similarcomponents, wherein:

FIG. 1 is an illustration of an Orthogonal Frequency DivisionMultiplexing (OFDM) transceiver chain suitable for the practice of theprinciples of the present disclosure;

FIG. 2 is an illustration of OFDM subcarriers;

FIG. 3 is an illustration of OFDM symbols in a time domain;

FIG. 4 is an illustration of single carrier frequency division multipleaccess transceiver chain;

FIG. 5 is an illustration of a Hybrid Automatic Repeat request (HARQ)transceiver chain;

FIG. 6 is an illustration of a four-channel HARQ transmission scheme;

FIG. 7 is an illustration of a Multiple Input Multiple Output (MIMO)system;

FIG. 8 is an illustration of a precoded MIMO system;

FIG. 9 is an illustration of LTE downlink control channel elements;

FIG. 10 is an illustration of LTE downlink subframe structure;

FIG. 11 illustrates a mapping scheme according to a first embodiment ofthe principles of the present disclosure;

FIG. 12 illustrates an interleaving scheme and a mapping schemeaccording to the first embodiment of the principles of the presentdisclosure;

FIG. 13 illustrates a sequence of steps in a process of mappingmodulation symbols according to the first embodiment of the principlesof the present disclosure;

FIG. 14 illustrates a sequence of steps in a process of decodingmodulation symbols according to a second embodiment of the principles ofthe present disclosure;

FIG. 15 illustrates a mapping scheme according to a fourth embodiment ofthe principles of the present disclosure; and

FIG. 16 illustrates a mapping scheme according to a fifth embodiment ofthe principles of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 illustrates an Orthogonal Frequency Division Multiplexing (OFDM)transceiver chain. In a communication system using OFDM technology, attransmitter chain 110, control signals or data 111 is modulated bymodulator 112 into a series of modulation symbols, that are subsequentlyserial-to-parallel converted by Serial/Parallel (S/P) converter 113.Inverse Fast Fourier Transform (IFFT) unit 114 is used to transfer thesignals from frequency domain to time domain into a plurality of OFDMsymbols. Cyclic prefix (CP) or zero prefix (ZP) is added to each OFDMsymbol by CP insertion unit 116 to avoid or mitigate the impact due tomultipath fading. Consequently, the signal is transmitted by transmitter(Tx) front end processing unit 117, such as an antenna (not shown), oralternatively, by fixed wire or cable. At receiver chain 120, assumingperfect time and frequency synchronization are achieved, the signalreceived by receiver (Rx) front end processing unit 121 is processed byCP removal unit 122. Fast Fourier Transform (FFT) unit 124 transfers thereceived signal from time domain to frequency domain for furtherprocessing.

In a OFDM system, each OFDM symbol consists of multiple sub-carriers.Each sub-carrier within an OFDM symbol carriers a modulation symbol.FIG. 2 illustrates the OFDM transmission scheme using sub-carrier 1,sub-carrier 2, and sub-carrier 3. Because each OFDM symbol has finiteduration in time domain, the sub-carriers overlap with each other infrequency domain. The orthogonality is maintained at the samplingfrequency assuming the transmitter and the receiver has perfectfrequency synchronization, as shown in FIG. 2. In the case of frequencyoffset due to imperfect frequency synchronization or high mobility, theorthogonality of the sub-carriers at sampling frequencies is destroyed,resulting in inter-carrier-interference (ICI).

A time domain illustration of the transmitted and received OFDM symbolsis shown in FIG. 3. Due to multipath fading, the CP portion of thereceived signal is often corrupted by the previous OFDM symbol. However,as long as the CP is sufficiently long, the received OFDM symbol withoutCP should only contain its own signal convoluted by the multipath fadingchannel. In general, a Fast Fourier Transform (FFT) is taken at thereceiver side to allow further processing frequency domain. Theadvantage of OFDM over other transmission schemes is its robustness tomultipath fading. The multipath fading in time domain translates intofrequency selective fading in frequency domain. With the cyclic prefixor zero prefix added, the inter-symbol-interference between adjacentOFDM symbols are avoided or largely alleviated. Moreover, because eachmodulation symbol is carried over a narrow bandwidth, it experiences asingle path fading. Simple equalization scheme can be used to combatfrequency selection fading.

Single carrier frequency division multiple access (SC-FDMA), whichutilizes single carrier modulation and frequency domain equalization isa technique that has similar performance and complexity as those of anOFDMA system. One advantage of SC-FDMA is that the SC-FDMA signal haslower peak-to-average power ratio (PAPR) because of its inherent singlecarrier structure. Low PAPR normally results in high efficiency of poweramplifier, which is particularly important for mobile stations in uplinktransmission. SC-FDMA is selected as the uplink multiple access schemein 3GPP long term evolution (LTE). An example of the transceiver chainfor SC-FDMA is shown in FIG. 4. At the transmitter side, the data orcontrol signal is serial to parallel (S/P) converted by a S/P convertor181. Discrete Fourier transform (DFT) will be applied to time-domaindata or control signal by a DFT transformer 182 before the time-domaindata is mapped to a set of sub-carriers by a sub-carrier mapping unit183. To ensure low PAPR, normally the DFT output in the frequency domainwill be mapped to a set of contiguous sub-carriers. Then IFFT, normallywith larger size than the DFT, will be applied by an IFFT transformer184 to transform the signal back to time domain. After parallel toserial (P/S) conversion by a P/S converter 185, cyclic prefix (CP) willbe added by a CP insertion unit 186 to the data or the control signalbefore the data or the control signal is transmitted to a transmissionfront end processing unit 187. The processed signal with a cyclic prefixadded is often referred to as a SC-FDMA block. After the signal passesthrough a communication channel 188, e.g., a multipath fading channel ina wireless communication system, the receiver will perform receiverfront end processing by a receiver front end processing unit 191, removethe CP by a CP removal unit 192, apply FFT by a FFT transformer 194 andfrequency domain equalization. Inverse Discrete Fourier transform (IDFT)196 will be applied after the equalized signal is demapped 195 infrequency domain. The output of IDFT will be passed for furthertime-domain processing such as demodulation and decoding.

In packet-based wireless data communication systems, control signalstransmitted through control channels, i.e., control channeltransmission, generally accompany data signals transmitted through datachannels, i.e., data transmission. Control channel information,including control channel format indicator (CCFI), acknowledgementsignal (ACK), packet data control channel (PDCCH) signal, carriestransmission format information for the data signal, such as user ID,resource assignment information, Payload size, modulation, HybridAutomatic Repeat-reQuest (HARQ) information, MIMO related information.

Hybrid Automatic Repeat reQuestion (HARQ) is widely used incommunication systems to combat decoding failure and improvereliability. Each data packet is coded using certain forward errorcorrection (FEC) scheme. Each subpacket may only contains a portion ofthe coded bits. If the transmission for subpacket k fails, as indicatedby a NAK in a feedback acknowledgement channel, a retransmissionsubpacket, subpacket k+1, is transmitted to help the receiver decode thepacket. The retransmission subpackets may contain different coded bitsthan the previous subpackets. The receiver may softly combine or jointlydecode all the received subpackets to improve the chance of decoding.Normally, a maximum number of transmissions is configured inconsideration of both reliability, packet delay, and implementationcomplexity.

Due to its simplicity, N-channel synchronous HARQ are often used inwireless communication systems. For example, synchronous HARQ has beenaccepted as the HARQ scheme for LTE uplink in 3GPP. FIG. 5 shows anexample of a 4-channel synchronous HARQ. Due to fixed timingrelationship between subsequent transmissions, the transmission slots inthe same HARQ channel exhibits an interlace structure. For example,interlace 0 consists of slot 0, 4, 8, . . . , 4k, . . . ; interlace 1consists of slot 1, 5, 9, . . . , 4k+1, . . . ; interlace 2 consists ofslot 2, 6, 10, . . . , 4k+2, . . . ; interlace 3 consists of slot 3, 7,11, . . . 4k+3, . . . . Let's take interlace 0 as an example. Asub-packet is transmitted in slot 0. After correctly decoding thepacket, the receiver sends back an ACK to the transmitter. Thetransmitter then can start a new packet at the next slot in thisinterlace, i.e., slot 4. However, the first subpacket transmitted inslot 4 is not correctly received. After the transmitter receives the NAKfrom the receiver, the transmitter transmits another sub-packet of thesame packet at the next slot in this interlace, i.e., slot 8. Sometimesa receiver might have difficulty in detecting the packet boundary, i.e.,whether a subpacket is the first sub-packet of a new packet or aretransmission sub-packet. To alleviate this problem, a new packetindicator may be transmitted in the control channel that carriestransmission format information for the packet. Sometimes, a moreelaborated version of HARQ channel information, such as sub-packet ID,or even HARQ channel ID, can be transmitted to help the receiver detectand decode the packet.

Multiple antenna communication systems, which is often referred to asmultiple input multiple output (MIMO), are widely used in wirelesscommunication to improve system performance. In a MIMO system, thetransmitter has multiple antennas capable of transmitting independentsignals and the receiver is equipped with multiple receive antennas.MIMO systems degenerates to single input multiple output (SIMO) if thereis only one transmission antenna or if there is only one stream of datatransmitted. MIMO systems degenerates to multiple input signle output(MISO) if there is only one receive antenna. MIMO systems degenerates tosingle input single output (SISO) if there is only one transmissionantenna and one receive antenna. MIMO technology can significantincrease throughput and range of the system without any increase inbandwidth or overall transmit power. In general, MIMO technologyincreases the spectral efficiency of a wireless communication system byexploiting the additional dimension of freedom in the space domain dueto multiple antennas. There are many categories of MIMO technologies.For example, spatial multiplexing schemes increase the transmission rateby allowing multiple data streaming transmitted over multiple antennas.Transmit diversity methods such as space-time coding take advantage ofspatial diversity due to multiple transmit antennas. Receiver diversitymethods utilizes the spatial diversity due to multiple receive antennas.Beamforming technologies improve received signal gain and reducinginterference to other users. Spatial division multiple access (SDMA)allows signal streams from or to multiple users to be transmitted overthe same time-frequency resources. The receivers can separate themultiple data streams by the spatial signature of these data streams.Note these MIMO transmission techniques are not mutually exclusive. Infact, many MIMO schemes are often used in an advanced wireless systems.

When the channel is favorable, e.g., the mobile speed is low, it ispossible to use closed-loop MIMO scheme to improve system performance.In a closed-loop MIMO systems, the receivers feedback the channelcondition and/or preferred Tx MIMO processing schemes. The transmitterutilizes this feedback information, together with other considerationssuch as scheduling priority, data and resource availability, to jointlyoptimize the transmission scheme. A popular closed loop MIMO scheme iscalled MIMO precoding. With precoding, the transmit data streams arepre-multiplied by a matrix before being passed on to the multipletransmit antennas. As shown in FIG. 6, assume there are Nt transmitantennas and Nr receive antennas. Denote the channel between the Nttransmit antennas and the Nr receive antennas as H. Therefore H is anNt×Nr matrix. If the transmitter has knowledge about H, the transmittercan choose the most advantageous transmission scheme according to H. Forexample, if maximizing throught is the goal, the precoding matrix can bechosen to be the right singular matrix of H, if the knowledge of H isavailable at the transmitter. By doing so, the effective channel for themultiple data streams at the receiver side can be diagonalized,eliminating the interference between the multiple data streams. However,the overhead required to feedback the exact value of H is oftenprohibitive. In order to reduce feedback overhead, a set of precodingmatrices are defined to quantize the space of the possible values that Hcould substantiate. With the quantization, a receiver feeds back thepreferred precoding scheme, normally in the form of the index of thepreferred precoding matrix, the rank, and the indices of the preferredprecoding vectors. The receiver may also feed back the associated CQIvalues for the preferred precoding scheme.

Another perspective of a MIMO system is whether the multiple datastreams for transmission are encoded separately or encoded together. Ifall the layers for transmission are encoded together, we call it asingle codeword (SCW) MIMO system. And we call it a multiple codeword(MCW) MIMO system otherwise. In the LTE downlink system, when singleuser MIMO (SU-MIMO) is used, up to 2 codewords can be transmitted to asingle UE. In the case that 2 codewords are transmitted to a UE, the UEneeds to acknowledge the two codewords separately. Another MIMOtechnique is called spatial division multiple access (SDMA), which isalso referred to as multi-user MIMO (MU-MIMO) sometimes. In SDMA,multiple data streams are encoded separately and transmitted todifferent intended receivers on the same time-frequency resources. Byusing different spatial signature, e.g., antennas, virtual antennas, orprecoding vectors, the receivers will be able to distinguish themultiple data streams. Moreover, by scheduling a proper group ofreceivers and choosing the proper spatial signature for each data streambased on channel state information, the signal of interest can beenhanced while the other signals can be enhanced for multiple receiversat the same time. Therefore the system capacity can be improved. Bothsingle user MIMO (SU-MIMO) and multi-user MIMO (MU-MIMO) are adopted inthe downlink of LTE. MU-MIMO is also adopted in the uplink of LTE whileSU-MIMO for LTE uplink is still under discussion.

In LTE systems, some resources, namely control channel elements, arereserved for downlink control channel transmission. Control channelcandidate set can be constructed based on the control channel elementsreserved for downlink control channels. Each downlink control channelcan be transmitted on one of the control channel candidate set. Anexample of control channel elements and control channel candidate set isshown in FIG. 9. In this example, 11 control channel candidate sets canbe constructed on 6 control channel elements. In the rest of thedocument, we will refer to these control channel candidate sets ascontrol channel resource sets, or simply, resource sets.

The downlink subframe structure in a 3GPP LTE system is shown in FIG.10. In the 3GPP LTE system, a time and frequency resource can be dividedinto a plurality of resource blocks 210 (RB). Each resource block 210can be further divided into a plurality of resource elements 211 in atime and frequency domain. As shown in FIG. 10, a single OFDM symbol canbe transmitted using a row of resource elements corresponding to thesame period of time. In a typical configuration, each subframe is 1 mslong, containing 14 OFDM symbols. Assume the OFDM symbols in a subframeare indexed from 0 to 13. Reference symbols (RS) for antenna 0 and 1 arelocated in OFDM symbol 0, 4, 7, and 11. If present, reference symbols(RS) for antennas 2 and 3 are located in OFDM symbol 2 and 8. Controlchannel signals, including Control Channel Format Indicator (CCFI),acknowledgement signal (ACK), packet data control channel (PDCCH)signal, are transmitted in the first one, or two, or three OFDM symbols.The number of OFDM symbols used for control channel signals is indicatedby CCFI. Data channel signals, i.e., Physical Downlink Shared Channel(PDSCH) signals, are transmitted in other OFDM symbols.

In this disclosure, we propose methods and apparatus to provide robustmapping from control channel and data channel to resources in OFDMsystems.

Aspects, features, and advantages of the subject matter of the presentdisclosure are readily apparent from the following detailed description,simply by illustrating a number of particular embodiments andimplementations, including the best mode contemplated for carrying outthe subject matter of the present disclosure. The subject matter of thepresent disclosure is also capable of other and different embodiments,and its several details can be modified in various obvious respects, allwithout departing from the spirit and scope of the disclosure.Accordingly, the drawings and description are to be regarded asillustrative in nature, and not as restrictive. The subject matter ofthe disclosure is illustrated by way of example, and not by way oflimitation, in the figures of the accompanying drawings. In thefollowing illustrations, we use the downlink subframe in 3GPP LTE systemas an example. However, the techniques illustrated here can certainly beapplied to uplink subframe structure, and in other systems wheneverapplicable.

FIG. 11 illustrates a scheme for mapping modulation symbols into aplurality of resource elements in an LTE downlink subframe according toa first embodiment of the principles of the present disclosure. Forillustration purpose, 14 OFDM symbols in the LTE downlink subframe areindexed from 0 to 13. The control channel signals may occupy the firstone, or two, or three OFDM symbols while the data channels may occupythe OFDM symbols that are not occupied by control channels. The LTEdownlink subframe can be divided into Region 1 consisting of theresource elements corresponding to OFDM symbols 3 through 13, and Region2 consisting of the resource elements corresponding to OFDM symbol 0, 1,and 2. Note here for ease of illustration, we assume control channelsand data channels are not transmitted in the same OFDM symbol.Nevertheless, all the embodiments in this disclosure are applicable tothe case where control channels and data channels do multiplex in thesame OFDM symbol. In general, Region 1 can be defined as the collectionof resource elements in a subframe that are used by data channeltransmission regardless of the value of certain control channelinformation carried in the said subframe, e.g., Control Channel FormatIndicator (CCFI). Region 2 can be defined as the collection of resourceelements in a subframe that may be used by data channel transmission ifthe said resource elements are not used by other overhead channels,which is indicated by certain control channel information carried in thesaid subframe, e.g., CCFI.

Note there may be multiple data channel transmissions in a subframe thatare multiplexed in the frequency domain using Orthogonal FrequencyDivision Multiple Access (OFDMA). For one data channel, assume there areN₁ resource elements available in Region 1 and N₂ resource elementsavailable in Region 2. The availability of the resource elements fordata transmission in Region 1 consisting of OFDM symbols 3 through 13 isindependent of any control channel information. The availability of theresource elements for data transmission in Region 2 may be, however,dependent upon some control channel information. In the first embodimentof LTE downlink subframe, the availability of the resource elements fordata transmission in OFDM symbols 0, 1, and 2 in Region 2 depends on thevalue of CCFI. For example, if CCFI indicates OFDM symbol 0 and 1 inRegion 2 are used for control channel signal transmission, then onlyresource elements in OFDM symbol 2 are available for data transmission.

For the easy of illustration, we number the modulation symbols that needto be mapped to resource elements from 0 to N−1, where N=N₁+N₂. FIG. 12illustrates the scheme for interleaving modulation symbols in a firststage and mapping the interleaved modulation symbols into a plurality ofresource elements in a second stage according to the first embodiment ofthe principles of the present disclosure. For the ease of illustration,the description in this disclosure can be viewed as the second stageoperation in FIG. 12 that illustrates the mapping from modulationsymbols to resources assuming a natural order or numbering of themodulation symbols. It is certainly straightforward for a person withordinary skill in the art, however, to apply the techniques in thisdisclosure to cases where the modulation symbols are not in the naturalorder. As shown in FIG. 12, by adding the first stage of modulationsymbol ordering or interleaving, the techniques described in thisdisclosure can be applied to the case of modulation symbols with adifferent order. Also note that in some other cases, the techniquesdescribed in this disclosure can be combined with other processing. Forexample, one might describe the mapping from modulation symbols toresource elements jointly for the first stage and the second stageoperations as shown in FIG. 12 without departing from the disclosure ofthe disclosure.

In the first embodiment according to the principles of the disclosure,the method of mapping of a plurality of modulation symbols to aplurality of resource elements contemplates segregating the plurality ofresource elements in a subframe into a plurality of resource regions.The mapping in at least one resource region in the said subframe isindependent of certain control channel information carried in the saidsubframe, while the mapping of modulation symbols to resource elementsin at least another resource region in the said subframe is dependent onthe said control channel information carried in the said subframe. FIG.11 shows an example of the first embodiment. As shown in FIG. 11, tworesource blocks (RBs) are allocated to a data transmission. Note thesetwo RBs does not need to be contiguous in frequency domain. Except theresources that are used for predefined overhead, e.g., reference signals(RSs), the other REs can be used for both control channel and datachannel transmission. In this example, we assume control channel signalscan only be transmitted in the first three OFDM symbols. And theallocation and size of the resources for control channel transmission isindicated by the control channel format indication (CCFI) that iscarried by the control channel signals. The resource elements (REs) inthese two RBs are divided into two regions. Region 1 consists of REscorresponding to the last eleven OFDM symbols (i.e., OFDM symbols 3through 11) in a subframe. Region 2 consists of REs corresponding to thefirst three OFDM symbols in a subframe. Note control and data aremultiplexed in Region 2 and the allocation and size of the resources forcontrol channel in Region 2 is indicated by CCFI. In other words, theallocation and size of the resources for data channel transmission inRegion 2 depend on CCFI. Before entering the modulator as shown in FIG.1, coded bits generated by information bits and channel coding schemeare rate matched, interleaved, and modulated for each transmission. Themodulation symbols may be further channel-interleaved. The modulationsymbols are mapped to the data REs (i.e., resource elements that areavailable for data channel transmission) in Region 1 in a fashion thatis independent of CCFI. For example, as shown in FIG. 11, modulationsymbols are mapped to available data REs in a row-wise manner.Specifically, modulation symbols 0-23 are mapped to the 24 data REs inthe 4-th OFDM symbol (i.e., OFDM symbol 3). Modulation symbols 24 -39are mapped to the 16 data REs in the 5-th OFDM symbol (i.e., OFDM symbol4). Modulation symbols 208-231 are mapped to the 24 data REs in the14-th OFDM symbol (i.e., OFDM symbol 13). Assume control channel (PDCCH)signals occupies the first 2 OFDM symbols (i.e., OFDM symbols 1 and 2),the REs in the third OFDM symbol can also be utilized for data channeltransmission. Thus, modulation symbol 232-255 are mapped to the 24available data REs in the third OFDM symbol (i.e., OFDM symbol 2). Notethat further channel interleaving and other processing of thesemodulation symbols can be performed, if desired. Preferably, theseprocessing should be limited to be within Region 2 to maintain theresource allocation and modulation symbol mapping in Region 1 to beindependent of CCFI. Note the aforementioned mapping method is just anillustration, different resource allocation and modulation mappingmethods can be applied without departing from the scope of thisdisclosure. The mapping from modulation symbols 0-231 to Region 1 inFIG. 11 can be any mapping, as long the mapping does not depend on CCFI.For example, we can map modulation symbols to REs in Region 1, startingfrom the last OFDM symbol. In that case, modulation symbols 0-23 aremapped to the last OFDM symbol (i.e., OFDM symbol 13); modulation symbol24-47 are mapped to the second to last OFDM symbol (i.e., OFDM symbol12); and modulation symbols 208-231 are mapped to the fourth OFDM symbol(i.e., OFDM symbol 11).

FIG. 13 illustrates a process for mapping modulation symbols accordingto the first embodiment of the principles of the present disclosure.First, at step S310, the data signals and the control signals to betransmitted are modulated into a plurality of modulation symbolsincluding data symbols and control symbols. At step 320, the availableresource elements for transmission in a subframe are divided to Region 1and Region 2. At step 330, the modulation symbols are mapped into Region1 and Region 2. Specifically, the mapping of modulation symbols intoRegion 1 is independent of the CCFI information carried in the controlsignals, and the mapping of modulation symbols into Region 2 isdependent upon the CCFI information carried in the control signals.Finally, at step 340, the modulation symbols mapped into the resourceelements are transmitted via a plurality of antennas.

In a second embodiment according to the principles of the presentdisclosure, an operation of a receiver of the multiple-region resourcemapping is illustrated in FIG. 14. For illustration purpose, the exampleas shown in FIG. 11 is used. At step S410, the receiver first decodesthe CCFI information that is carried by the control channel signals.Based on the detected CCFI, the receiver can figure out which resourceelements are allocated for data channel transmission in Region 2. Atstep S420, the receiver collects the received modulation symbols onavailable data REs in Region 2 according to the mapping from modulationsymbols to data REs in Region 2. The mapping scheme may be pre-definedbefore the transmission process is started. Alternatively, thetransmitter may transmit a control channel signal containing theinformation regarding the mapping scheme. At step S430, the receiveralso collects the modulation symbols on available data REs in Region 1to produce a first data packet according to the mapping scheme frommodulation symbols to data REs in Region 1. The receiver will thenattempt to decode the first data packet consisting of the modulationsymbols from Region 1 only at step S440. At step S450, the receiverchecks whether the first data packet decodes by using cyclic redundancycheck (CRC) function. If the first data packet decodes, i.e., cyclicredundancy check (CRC) checks, then the receiver can pass the decodedpacket to upper layer for further processing at step S460. Otherwise, atstep S470, the receiver produces a second data packet consisting of themodulation symbols in both Region 1 and Region 2 and attempt to decodethe second data packet. At step 480, the receiver passes the decodedpacket to upper layer for further processing at step S460.Alternatively, the receiver can first attempt to decode the data packetwith modulation symbols in both Region 1 and Region 2. If the decodingis successful, i.e., CRC checks, then the receiver can pass the decodedpacket to upper layer for further processing. Otherwise, the receiverwill attempt to decode the data packet with the modulation symbols inRegion 1 only. Alternatively, erasure detection or CRC can be applied tothe detection of the CCFI. In the case that the receiver does notsuccessfully detect the CCFI, i.e., if CCFI erasure or CCFI detectionerror occurs, the receiver only uses modulation symbols in Region 1 todecode the packet. Otherwise, the receiver uses modulation symbols inboth Region 1 and Region 2 to decode the packet.

In a third embodiment according to the principles of the presentdisclosure, the modulation symbols 0, 1, . . . , N₁−1 are mapped toRegion 1 and modulation symbols N₁, N₁+1, . . . , N−1 are mapped toRegion 2. Again using FIG. 12 as an example, there are 256 modulationsymbols in total for this data transmission. The first 232 modulationsymbols are mapped to REs in Region 1 and the other 24 modulationsymbols are mapped to REs in Region 2. Note that the number ofmodulation symbols that can be transmitted equals to the number of REsavailable for data transmission. With the two-region approach,regardless of the value of CCFI, the first N₁ modulation symbols aremapped to the N₁ REs in Region 1. The number of available data REs andthe number of modulation symbols transmitted in Region 2, however,depend on the value of CCFI.

In a fourth embodiment according to the principles of the presentdisclosure, the method of mapping of modulation symbols to resourceelements in a subframe contemplates segregating the resource elements inthe subframe into a plurality of resource regions with the mapping ofthe modulation symbols in at least one resource region in the subframeutilizing the OFDM symbols in an increasing order while the mapping ofthe modulation symbols to resource elements in at least another resourceregion in the said subframe utilizing the OFDM symbols in a decreasingorder. For example, in an LTE downlink subframe, the mapping ofmodulation symbols in Region 1 starts from REs in OFDM symbol 3 whilethe OFDM symbols are filled in an increasing order while the mapping ofmodulation symbols in Region 2 starts from REs in OFDM symbol 2 whilethe OFDM symbols are filled in a decreasing order. In other words, theorder that the OFDM symbols are filled with modulation symbols are 3, 4,5, 6, 7, 8, 9, 10, 11, 12, 13, 2, 1, 0. Note that the availability ofREs in Region 2 (OFDM symbol 0, 1, 2) depends on the control channelformat indicator (CCFI). This mapping method is especially useful whenthere are multiple code blocks in the data transmission. By mapping codeblocks to OFDM symbols that are ordered sequentially in time domain, thereceiver can start decoding of some code block before receiving thewhole subframe. The fourth embodiment is also illustrated in FIG. 15.Again, the order of mapping of modulation symbols to REs in frequencydomain can be changed without departing from this disclosure. Forexample, FIG. 15 shows modulation symbol 0 to 23 are mapped to REs inOFDM symbol 3 in sequential order along the frequency axis. However, theorder of mapping in frequency domain can be changed, e.g., by frequencydomain interleaving, without departing from the scope of thisdisclosure.

In a fifth embodiment according to the principles of the presentdisclosure, the mapping of modulation symbols of each code block toresource elements in at least one resource region is independent ofcertain control channel information carried in the said subframe. Anexample is illustrated in FIG. 16. In this example, modulation symbolsthat carry coded bits for code block A are transmitted on OFDM symbol 3and 4 in Region 1, and OFDM symbol 2 in Region 2. Modulation symbolsthat carry coded bits for code block B are transmitted on OFDM symbol 4and 5 in Region 1, and OFDM symbol 2 in Region 2. Modulation symbolsthat carry coded bits for code block C are transmitted on OFDM symbol 5and 6 in Region 1, and OFDM symbol 2 in Region 2. By doing so, thereceiver can start decoding some code blocks before receiving the wholesubframe. For example, the receiver can start decoding of code block Aafter receiving and demodulating data REs in OFDM symbol 2, 3, and 4

In a sixth embodiment according to the principles of the presentdisclosure, the mapping of modulation symbols within each code blockinto resource elements within at least one resource region beingindependent of certain control channel information carried in the saidsubframe while the mapping of modulation symbols of each code block intoresource elements within at least another resource region beingdependent of certain control channel information carried in the saidsubframe. Again using FIG. 16 as an example, the number and location ofdata REs for code block A, B, and C in Region 2 depend on the CCFIinformation, while the number and location of data REs for code block A,B, and C in Region 1 does not depend on the CCFI information.

In a seventh embodiment according to the principles of the presentdisclosure, the number of data REs in at least one resource region amonga plurality of resource regions is allocated roughly equally among themultiple code blocks to ensure about equal error protection on each codeblock. Since there is only one CRC for the whole transport block, it isimportant for each code block to receive as much error protection aspossible. Note that the number of available data REs may not bedivisible by the number of code blocks. So, we can only ensure roughlyequal number of data REs assigned to each code block. Assuming there areN₁ modulation symbols available for data transmission in Region 1 and N₂modulation symbols available for data transmission in Region 2. Assumethere are N_(seg) code blocks. Define ┌x┐ as the smallest integer thatis larger than or equal to x. Define └x┘ as the largest integer that issmaller than or equal to x. Define x mod y as the remainder of

$\frac{x}{y}.$As an example, the number of data REs assigned to code block j in Region1, M_(j,1), could be given by

$\begin{matrix}{M_{j,1} = \left\{ {\begin{matrix}{\left\lceil {N_{1}/N_{seg}} \right\rceil,} & {0 \leq j < {N_{1}{mod}\; N_{seg}}} \\{\left\lfloor {N_{1}/N_{seg}} \right\rfloor,} & {{N_{1}{mod}\; N_{seg}} \leq j < N_{seg}}\end{matrix}.} \right.} & (1)\end{matrix}$Similarly, the number of data REs assigned to code block j in Region 2,M_(j,2), could be given by

$\begin{matrix}{M_{j,2} = \left\{ {\begin{matrix}{\left\lceil {N_{2}/N_{seg}} \right\rceil,} & {0 \leq j < {N_{2}{mod}\; N_{seg}}} \\{\left\lfloor {N_{2}/N_{seg}} \right\rfloor,} & {{N_{2}{mod}\; N_{seg}} \leq j < N_{seg}}\end{matrix}.} \right.} & (2)\end{matrix}$Note that in this embodiment, we assign a slightly larger number, i.e.,┌N₁/N_(seg)┐, of data REs to the code blocks at the beginning of Region1 and a slightly smaller number, i.e., └N₁/N_(seg)┘, of data REs to thecode blocks in the end of Region 1. This scheme works well if the codeblocks at the beginning may have larger sizes than the code blocks inthe end. Alternatively, we could assign the slightly smaller number ofdata REs to the code blocks at the beginning and the slightly largernumber of data REs to the code blocks in the end. This scheme works wellif the code blocks in the beginning may have smaller sizes than the codeblocks in the end. In that case, the number of data REs assigned to codeblock j in Region 1, M_(j,1), could be given by

$\begin{matrix}{M_{j,1} = \left\{ {\begin{matrix}{\left\lfloor {N_{1}/N_{seg}} \right\rfloor,} & {0 \leq j < \left( {N_{seg} - {N_{1}{mod}\; N_{seg}}} \right)} \\{\left\lceil {N_{1}/N_{seg}} \right\rceil,} & {\left( {N_{seg} - {N_{1}{mod}\; N_{seg}}} \right) \leq j < N_{seg}}\end{matrix}.} \right.} & (3)\end{matrix}$Similarly, the number of data REs assigned to code block j in Region 2,M_(j,2), could be given by

$\begin{matrix}{M_{j,2} = \left\{ {\begin{matrix}{\left\lfloor {N_{2}/N_{seg}} \right\rfloor,} & {0 \leq j < \left( {N_{seg} - {N_{2}{mod}\; N_{seg}}} \right)} \\{\left\lceil {N_{2}/N_{seg}} \right\rceil,} & {\left( {N_{seg} - {N_{2}{mod}\; N_{seg}}} \right) \leq j < N_{seg}}\end{matrix}.} \right.} & (4)\end{matrix}$Note this embodiment is still applicable when there is only one resourceregion, i.e., all data REs belong to the same resource region. Forexample, in the case of only one resource region, the number of dataresource elements is almost equally allocated among the multiple codeblocks. The number of data resource elements of code block j can begiven by Equation (1). Alternatively, the number of data resourceelements of code block j can be given by Equation (3). Note that for thecase of only one resource region, N₁ is the total number of resourceelements.

In an eighth embodiment according to the principles of the presentdisclosure, the number of coded bits, or the number of modulationpositions in modulation symbols, in at least one resource region isallocated roughly equally among the multiple code blocks to ensure aboutequal error protection on each code block. For example, assume themodulation order is L, e.g., L=4 for 16 QAM. A modulation position isone of the L bits that an L-th order modulation symbol carries. Forexample, a QPSK modulation symbol (L=2) has 2 modulation positions, eachone corresponds to a bit that is carried by the modulation symbol. A16-QAM modulation symbol (L=4) can carry 4 bits. Thus there are 4modulation positions in a 16-QAM modulation symbol. Therefore, a totalnumber of N₁×L coded bits can be transmitted in Region 1. A total numberof N₂×L coded bits can be transmitted in Region 2. The resourceassignment can be done on a coded-bit basis. As an example, the numberof coded bits assigned to code block j in Region 1, M_(j,2), could begiven by

$\begin{matrix}{M_{j,1} = \left\{ {\begin{matrix}{\left\lceil {\left( {N_{1} \times L} \right)/N_{seg}} \right\rceil,} & {0 \leq j < \left( {\left( {N_{1} \times L} \right)\mspace{14mu}{mod}\mspace{14mu} N_{seg}} \right)} \\{\left\lfloor {\left( {N_{1} \times L} \right)/N_{seg}} \right\rfloor,} & {\left( {\left( {N_{1} \times L} \right)\mspace{14mu}{mod}\mspace{14mu} N_{seg}} \right) \leq j < N_{seg}}\end{matrix}.} \right.} & (5)\end{matrix}$Similarly, the number of coded bits assigned to code block j in Region2, M_(j,2), could be given by

$\begin{matrix}{M_{j,2} = \left\{ {\begin{matrix}{\left\lceil {\left( {N_{2} \times L} \right)/N_{seg}} \right\rceil,} & {0 \leq j < \left( {\left( {N_{2} \times L} \right)\mspace{14mu}{mod}\mspace{14mu} N_{seg}} \right)} \\{\left\lfloor {\left( {N_{2} \times L} \right)/N_{seg}} \right\rfloor,} & {\left( {\left( {N_{2} \times L} \right)\mspace{14mu}{mod}\mspace{14mu} N_{seg}} \right) \leq j < N_{seg}}\end{matrix}.} \right.} & (6)\end{matrix}$Note that in this embodiment, we assign a slightly larger number, i.e.,┌(N₁×L)/N_(seg)┐, of coded bits to the code blocks at the beginning anda slightly smaller number, i.e., └(N₁×L)/N_(seg)┘, of coded bits to thecode blocks in the end. This scheme works well if the code blocks at thebeginning may have larger sizes than the code blocks in the end.Alternatively, we could assign the slightly smaller number of coded bitsto the code blocks at the beginning and the slightly larger number ofcoded bits to the code blocks in the end. This scheme works well if thecode blocks in the beginning may have smaller sizes than the code blocksin the end. In that case, the number of coded bits assigned to codeblock j in Region 1, M_(j,1), could be given by

$\begin{matrix}{M_{j,1} = \left\{ {\begin{matrix}{\left\lfloor {\left( {N_{1} \times L} \right)/N_{seg}} \right\rfloor,} & {0 \leq j < \left( {N_{seg} - {\left( {N_{1} \times L} \right)\mspace{14mu}{mod}\mspace{14mu} N_{seg}}} \right)} \\{\left\lceil {\left( {N_{1} \times L} \right)/N_{seg}} \right\rceil,} & {\left( {N_{seg} - {\left( {N_{1} \times L} \right)\mspace{14mu}{mod}\mspace{14mu} N_{seg}}} \right) \leq j < N_{seg}}\end{matrix}.} \right.} & (7)\end{matrix}$Similarly, the number of data REs assigned to code block j in Region 2,M_(j,2), could be given by

$\begin{matrix}{M_{j,2} = \left\{ {\begin{matrix}{\left\lfloor {\left( {N_{2} \times L} \right)/N_{seg}} \right\rfloor,} & {0 \leq j < \left( {N_{seg} - {\left( {N_{2} \times L} \right)\mspace{14mu}{mod}\mspace{14mu} N_{seg}}} \right)} \\{\left\lceil {\left( {N_{2} \times L} \right)/N_{seg}} \right\rceil,} & {\left( {N_{seg} - {\left( {N_{2} \times L} \right)\mspace{14mu}{mod}\mspace{14mu} N_{seg}}} \right) \leq j < N_{seg}}\end{matrix}.} \right.} & (8)\end{matrix}$Again, note this embodiment is still applicable when there is only oneresource region, i.e., all data REs belong to the same resource region.For example, in the case of only one resource region, the number ofcoded bit is almost equally allocated among the multiple code blocks.The number of coded bits assigned to code block j can be given byEquation (5). Alternatively, the number of coded bits assigned to codeblock j can be given by Equation (7). Note that for the case of only oneresource region, N₁ is the total number of resource elements.

In a ninth embodiment according to the principles of the presentdisclosure, the number of data REs in at least one resource region isallocated to achieve roughly equal coding rate among the multiple codeblocks to ensure about equal error protection on each code block. Forexample, the number of data REs assigned to code block j in Region 1,M_(j,1), could be given by

$\begin{matrix}{M_{j,1} = \left\{ {\begin{matrix}{{\left\lfloor {\left( {N_{1} \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor + 1},} & {0 \leq j < X_{1}} \\{\left\lceil {\left( {N_{1} \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rceil,} & {X_{1} \leq j < N_{seg}}\end{matrix},} \right.} & (9)\end{matrix}$where K_(j) is the information block size of the code block j and

$\begin{matrix}{X_{1} = {N_{1} - {\sum\limits_{j = 0}^{N_{seg} - 1}\left\lfloor {\left( {N_{1} \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor}}} & (10)\end{matrix}$is the number such that Σ_(j=0) ^(N) ^(seg) ⁻¹M_(j,1)=N₁. Note, althoughnot required, the definition of K_(j) preferably includes tail bits.

Similarly, the number of data REs assigned to code block j in Region 2,M_(j,2), could be given by

$\begin{matrix}{M_{j,2} = \left\{ {\begin{matrix}{{\left\lfloor {\left( {N_{2} \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor + 1},} & {0 \leq j < X_{2}} \\{\left\lceil {\left( {N_{2} \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rceil,} & {X_{2} \leq j < N_{seg}}\end{matrix},} \right.} & (11)\end{matrix}$where K_(j) is the information block size of the code block j and

$\begin{matrix}{X_{2} = {N_{2} - {\sum\limits_{j = 0}^{N_{seg} - 1}\left\lfloor {\left( {N_{2} \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor}}} & (12)\end{matrix}$is the number such that Σ_(j=0) ^(N) ^(seg) ⁻¹M_(j,2)=N₂.

Note that in this embodiment, we assign a slightly larger number of dataREs to the code blocks at the beginning and a slightly smaller number ofdata REs to the code blocks in the end. This scheme works well if thecode blocks at the beginning may have larger sizes than the code blocksin the end. Alternatively, we could assign the slightly smaller numberof data REs to the code blocks at the beginning and the slightly largernumber of data REs to the code blocks in the end. This scheme works wellif the code blocks in the beginning may have smaller sizes than the codeblocks in the end. In that case, the number of data REs assigned to codeblock j in Region 1, M_(j,1), could be given by

$\begin{matrix}{M_{j,1} = \left\{ {\begin{matrix}{{\left\lfloor {\left( {N_{1} \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor + 1},} & {0 \leq j < {N_{seg} - X_{1}}} \\{\left\lceil {\left( {N_{1} \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rceil,} & {{N_{seg} - X_{1}} \leq j < N_{seg}}\end{matrix}.} \right.} & (13)\end{matrix}$Similarly, the number of data REs assigned to code block j in Region 2,M_(j,2), could be given by

$\begin{matrix}{M_{j,2} = \left\{ {\begin{matrix}{{\left\lfloor {\left( {N_{2} \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor + 1},} & {0 \leq j < {N_{seg} - X_{2}}} \\{\left\lceil {\left( {N_{2} \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rceil,} & {{N_{seg} - X_{2}} \leq j < N_{seg}}\end{matrix}.} \right.} & (14)\end{matrix}$Again, note this embodiment is still applicable when there is only oneresource region, i.e., all data REs belong to the same resource region.For example, in the case of only one resource region, the number of dataREs is allocated to achieve roughly equal coding rate. The number ofdata REs assigned to code block j can be given by Equation (9).Alternatively, the number of data REs assigned to code block j can begiven by Equation (13). Note that for the case of only one resourceregion, N₁ is the total number of resource elements.

In a tenth embodiment according to the principles of the presentdisclosure, the number of coded bits, or the number of modulationpositions in modulation symbols, in at least one resource region isallocated to achieve roughly equal coding rate among the multiple codeblocks to ensure about equal error protection on each code block. Forexample, the number of coded bits assigned to code block j in Region 1,M_(j,1), could be given by

$\begin{matrix}{M_{j,1} = \left\{ {\begin{matrix}{{\left\lfloor {\left( {N_{1} \times L \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor + 1},} & {0 \leq j < Y_{1}} \\{\left\lceil {\left( {N_{1} \times L \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rceil,} & {Y_{1} \leq j < N_{seg}}\end{matrix},{where}} \right.} & (15) \\{Y_{1} = {\left( {N_{1} \times L} \right) - {\sum\limits_{j = 0}^{N_{seg} - 1}\left\lfloor {\left( {N_{1} \times L \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor}}} & (16)\end{matrix}$is the number such that Σ_(j=0) ^(N) ^(seg) ⁻¹M_(j,1)=N₁×L.

Similarly, the number of coded bits assigned to code block j in Region2, M_(j,2), could be given by

$\begin{matrix}{M_{j,2} = \left\{ {\begin{matrix}{{\left\lfloor {\left( {N_{2} \times L \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor + 1},} & {0 \leq j < Y_{2}} \\{\left\lceil {\left( {N_{2} \times L \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rceil,} & {Y_{2} \leq j < N_{seg}}\end{matrix},{where}} \right.} & (17) \\{Y_{2} = {\left( {N_{2} \times L} \right) - {\sum\limits_{j = 0}^{N_{seg} - 1}\left\lfloor {\left( {N_{2} \times L \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor}}} & (18)\end{matrix}$is the number such that Σ_(j=0) ^(N) ^(seg) ⁻¹M_(j,2)=N₂×L.

Note that in this embodiment, we assign a slightly larger number ofcoded bits to the code blocks at the beginning and a slightly smallernumber of coded bits to the code blocks in the end. This scheme workswell if the code blocks at the beginning may have larger sizes than thecode blocks in the end. Alternatively, we could assign the slightlysmaller number of coded bits to the code blocks at the beginning and theslightly larger number of coded bits to the code blocks in the end. Thisscheme works well if the code blocks in the beginning may have smallersizes than the code blocks in the end. In that case, the number of codedbits assigned to code block j in Region 1, M_(j,1), could be given by

$\begin{matrix}{M_{j,1} = \left\{ {\begin{matrix}{\left\lfloor {\left( {N_{1} \times L \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor,} & {0 \leq j < {N_{seg} - Y_{1}}} \\{\left\lfloor {\left( {N_{1} \times L \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor,{+ 1}} & {{N_{seg} - Y_{1}} \leq j < N_{seg}}\end{matrix}.} \right.} & (19)\end{matrix}$Similarly, the number of coded bits assigned to code block j in Region2, M_(j,2), could be given by

$\begin{matrix}{M_{j,2} = \left\{ {\begin{matrix}{\left\lfloor {\left( {N_{2} \times L \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor,} & {0 \leq j < {N_{seg} - Y_{2}}} \\{\left\lfloor {\left( {N_{2} \times L \times K_{j}} \right)/{\sum\limits_{i = 0}^{N_{seg} - 1}K_{i}}} \right\rfloor,{+ 1}} & {{N_{seg} - Y_{2}} \leq j < N_{seg}}\end{matrix}.} \right.} & (20)\end{matrix}$Again, note this embodiment is still applicable when there is only oneresource region, i.e., all data REs belong to the same resource region.For example, in the case of only one resource region, the number ofcoded bits is allocated to achieve roughly equal coding rate among themultiple code blocks. The number of coded bits assigned to code block jcan be given by Equation (15). Alternatively, the number of data REsassigned to code block j can be given by Equation (19). Note that forthe case of only one resource region, N₁ is the total number of resourceelements.

In an eleventh embodiment according to the principles of the presentdisclosure, only REs in Region 1 are used for certain datatransmissions. In this case, the danger of performance degradation dueto CCFI error can be completely removed, assuming downlink resourceassignment and transmission format are known to the receiver already.

What is claimed is:
 1. A method for transmitting bits by using aplurality of resources in a wireless communication system, the methodcomprising: segmenting the bits to be transmitted into a plurality ofcode blocks; encoding the bits in each code block; determining a numberof bits in each of the plurality of code blocks, wherein the number ofbits in at least one code block at an end of the plurality of codeblocks is determined based on ceiling function of N_(seg) and N₁, anumber of bits in at least one code block at a beginning of theplurality of code blocks is determined based on floor function ofN_(seg) and N₁, where N₁ is associated with a number of symbolsavailable for data transmission and N_(seg) is associated with a numberof code blocks; and transmitting the determined number of bits for eachcode block to a receiver via one or more antennas.
 2. The method ofclaim 1, wherein the number of the bits is a multiple of modulationorder.
 3. The method of claim 1, wherein at least one code block at abeginning of the plurality of code blocks and at least one code block inan end of the plurality of code blocks are determined based onsubtracting a value based N₁ modulo N_(seg) from N_(seg).
 4. The methodof claim 1, wherein the bits are transmitted through a sub-frame unitincluding a first resource region for information bits and a secondresource region for control bits, and wherein the control bits comprisea control channel format indication and the control channel formatindication indicates a number of multiplexing symbols used for thecontrol bits.
 5. The method of claim 4, wherein the information bits aremapped to the first resource region in an increasing order starting froma multiplexing symbol having a smallest index in a time domain.
 6. Themethod of claim 1, further comprising: interleaving the encoded bits;modulating the interleaved bits to generate modulation symbols; andmapping the modulation symbols to resources assigned to the code blocks.7. An apparatus for transmitting bits by using a plurality of resourcesin a wireless communication system, the apparatus comprising: an encoderconfigured to segment the bits to be transmitted into a plurality ofcode blocks and encode the bits in each code block; a controllerconfigured to determining a number of bits in each of the plurality ofcode blocks, wherein the number of bits in at least one code block at anend of the plurality of code blocks is determined based on ceilingfunction of N_(seg) and N₁, a number of bits in at least one code blockat a beginning of the plurality of code blocks is determined based onfloor function of N_(seg) and N₁, where N₁ is associated with a numberof symbols available for data transmission and N_(seg) is associatedwith a number of code blocks; and a transmitter configured to transmitthe determined number of bits for each code block to a receiver via oneor more antennas.
 8. The apparatus of claim 7, wherein the number of thebits is a multiple of modulation order.
 9. The apparatus of claim 7,wherein at least one code block at a beginning of the plurality of codeblocks and at least one code block in an end of the plurality of codeblocks are determined based on subtracting a value based N₁ moduloN_(seg) from N_(seg).
 10. The apparatus of claim 7, wherein the bits aretransmitted through a sub-frame unit including a first resource regionfor information bits and a second resource region for control bits,wherein the control bits comprise a control channel format indicationand the control channel format indication indicates a number ofmultiplexing symbols used for the control bits.
 11. The apparatus ofclaim 10, wherein the information bits are mapped to the first resourceregion in an increasing order starting from a multiplexing symbol havinga smallest index in a time domain.
 12. The apparatus of claim 7, furthercomprising: an interleaver configured to interleave the encoded bits; amodulator configured to modulate the interleaved bits to generatemodulation symbols; and a mapper configured to map the modulationsymbols to resources assigned to the code blocks.
 13. A method forreceiving bits transmitted by a plurality of resources in a wirelesscommunication system, the method comprising: receiving the bits, whichare segmented to be transmitted into a plurality of code blocks andencoded in each code block, from a transmitter via one or more antennas;and decoding the bits in each code block according to a determinednumber of bits which are encoded in each of the plurality of codeblocks, wherein the number of bits in at least one code block at an endof the plurality of code blocks is determined based on ceiling functionof N_(seg) and N₁, a number of bits in at least one code block at abeginning of the plurality of code blocks is determined based on floorfunction of N_(seg) and N₁, and where N₁ is associated with a number ofsymbols available for data transmission and N_(seg) is associated with anumber of code blocks.
 14. The method of claim 13, wherein the number ofthe bits is a multiple of modulation order.
 15. The method of claim 13,wherein at least one code block at a beginning of the plurality of codeblocks and at least one code block in an end of the plurality of codeblocks are determined based on subtracting a value based N₁ moduloN_(seg) from N_(seg).
 16. The method of claim 13, wherein the bits arereceived through a sub-frame unit including a first resource region forinformation bits and a second resource region for control bits, andwherein the control bits comprise a control channel format indicationand the control channel format indication indicates a number ofmultiplexing symbols used for the control bits.
 17. The method of claim16, wherein the information bits are mapped to the first resource regionin an increasing order starting from a multiplexing symbol having asmallest index in a time domain.
 18. The method of claim 13, furthercomprising: demapping resources assigned to the code blocks intomodulation symbols. demodulating the modulation symbols into the bits;and deinterleaving the bits.
 19. An apparatus for receiving informationbits transmitted by a plurality of resources in a wireless communicationsystem, the apparatus comprising: a receiver configured to receive thebits, which are segmented to be transmitted into a plurality of codeblocks and encoded in each code block, from a transmitter via one ormore antennas; and a decoder configured to decode the bits in each codeblock according to a determined number of bits which are encoded in eachof the plurality of code blocks, wherein the number of bits in at leastone code block at an end of the plurality of code blocks is determinedbased on ceiling function of N_(seg) and N₁, a number of bits in atleast one code block at a beginning of the plurality of code blocks isdetermined based on floor function of N_(seg) and N₁, and where N₁ isassociated with a number of symbols available for data transmission andN_(seg) is associated with a number of the plurality of code blocks. 20.The apparatus of claim 19, wherein the number of the bits is a multipleof modulation order.
 21. The apparatus of claim 19, wherein at least onecode block at a beginning of the plurality of code blocks and at leastone code block in an end of the plurality of code blocks are determinedbased on subtracting a value based N₁ modulo N_(seg) from N_(seg). 22.The apparatus of claim 19, wherein the bits are received through asub-frame unit including a first resource region for information bitsand a second resource region for control bits, and wherein the controlbits comprise a control channel format indication and the controlchannel format indication indicates a number of multiplexing symbolsused for the control bits.
 23. The apparatus of claim 22, wherein theinformation bits are mapped to the first resource region in anincreasing order starting from a multiplexing symbol having a smallestindex in a time domain.
 24. The apparatus of claim 19, furthercomprising: a demapper configured to demap resources assigned to theplurality of code blocks into modulation symbols, a demodulatorconfigured to demodulate the modulation symbols into the bits; and adeinterleaver configured to deinterleave the bits.